This invention pertains to signalling systems and more particularly to signalling systems for use in existing cable television systems.
Signalling systems between a central station and a plurality of remote stations have many applications. For example, in hotels and motels it is often necessary to turn off power consuming devices such as air conditioners when the room is vacant and not rely on the occupant to do so upon leaving the room. It can be used in hospitals for nurse calling or even in apartment buildings for signalling between a doorman and the tenants. Most systems require a complete wiring to set up the system. Such wiring is usually expensive. In buildings supplied with cable television, this wiring generally runs in parallel with the television cable.